The long term objective of this research is to characterize the role of vasopressin in cognitive functioning. There is a growing body of literature which demonstrates that vasopressin administration does affect performance on cognitive tasks in humans and animals. However, problems in both areas of research have limited the conclusions which may be drawn concerning this putative role. In the animal studies, the reliance on aversively motivated tasks, combined with the use of ambiguous measures of memory (e.g. extinction rate) have made it difficult to determine the generality or the nature of the observed behavioral effects. In the human research, the relative lack of studies using unimpaired subjects as well as the often arbitrary choice of cognitive measures here too prevent a more detailed description of vasopressin's cognitive effect. The research proposed here is designed to assess vasopressin's effect on the acquisition, storage, and retrieval of information in studies involving human and animal subjects. Cognitive tests were chosen for the human study that measure component processes that have been shown to be particularly sensitive to pharmacological and neuropathological insult. The animal tests were selected, in part, to provide parallel measures of these processes. In addition the animal paradigms were designed to clarify the generality of vasopressin's effect on learning and memory; for this reason tasks were chosen that involve either appetitive reinforcement or no overt reinforcement. Both studies include measures of (1) automatic and effortful processing, (2) incidental and intentional learning, and (3) working and reference memory. An integration of the animal and human data concerning the influence of these neuropeptides on learning and memory is important for a thorough understanding of the psychobiology of cognition as well as for the development of pharmacological treatments for cognitive dysfunction.